1. Field of the Invention
This invention relates to injection catheters and, more particularly, to a novel subcutaneous peritoneal injection catheter apparatus and method for providing injection access to the peritoneal cavity.
2. The Prior Art
The peritoneum is the largest serous membrane in the body and consists, in the male, of a closed sac, a part of which is applied against the abdominal parietes, while the remainder is reflected over the contained viscera. In the female, the peritoneum is not a closed sac, since the free ends of the uterine tubes open directly into the peritoneal cavity. The part which lines the abdominal wall is named the parietal peritoneum; that which is reflected over the contained viscera constitutes the visceral peritoneum. The space between the parietal and visceral layers of the peritoneum is named the peritoneal cavity; but under normal conditions, this cavity is merely a potential one, since the parietal and visceral layers are in contact.
For a number of years, it has been well-known that the peritoneal membrane will function fairly effectively as an ion exchange membrane for various purposes. As early as 1923, peritoneal dialysis (an artificial kidney format) was first applied clinically. The first peritoneal access device was a piece of rubber tubing temporarily sutured in place. As early as 1960, peritoneal dialysis was becoming an established form of artificial kidney therapy and, in order to lessen the discomfort of repeated, temporary punctures into the peritoneal cavity, various access devices permitting the painless insertion of the acute or temporary peritoneal catheters were developed.
One known peritoneal access device consists of a short, "golf tee" design that is adapted to be placed under the skin with a hollow tubular portion extending just into the peritoneal cavity. This device is designed specifically to allow the insertion of an acute peritoneal catheter (a Trocath) through the skin and down through this access tubing directly into the peritoneal cavity. Another device consists of a catheter buried underneath the skin and extending into the peritoneal cavity via a long tubing. Peritoneal dialysis is performed by inserting a large needle into the subcutaneous portion of the catheter.
All of the devices known were designed with one purpose in view: peritoneal dialysis, and are used almost exclusively by one group of patients, those with End-Stage Renal Disease (ESRD), whose kidney function will never return. In simple terms, therefore, the access devices to the peritoneal cavity plus the peritoneal cavity itself constitute an artificial kidney.
A variety of drugs or other fluids are frequently added to the large volumes of peritoneal dialysis solutions and are thus instilled (injected) into the peritoneal cavity for various therapeutic reasons. Some examples of these drugs are antibiotics, amino acids, and insulin (for diabetics). However, such therapeutic maneuvers are fortuitous in that the clinician is simply taking advantage of a particular situation, that is, a peritoneal access device emplaced in a particular group of patients.
However, there are cogent reasons for not using existing, permanent peritoneal access devices for simple drug injections in a wide variety of patients not suffering ESRD. Most of these devices have what might be termed a relatively large internal volume, that is, it would require anywhere between about five and twenty milliliters, depending upon the device, to fill the device with fluid. This volume which is a dead volume or dead space, is a very real hindrance in that the injected fluid may simply remain within the device itself instead of entering the peritoneal cavity.
In view of the foregoing, it would be an advancement in the art to provide a novel subcutaneous peritoneal injection catheter which may be readily implanted underneath the skin and provide direct access into the peritoneal cavity. It would also be an advancement in the art to provide a subcutaneous peritoneal injection catheter having a relatively small internal volume while providing a relatively enlarged target area. Such a novel subcutaneous peritoneal injection catheter apparatus and method is disclosed and claimed herein.